How to make this recipe

In a cocktail shaker, combine the gin, elderflower liqueur, fresh grapefruit juice, Simple Syrup, fresh lemon juice, orange bitters and egg white and shake well. Add ice to the shaker and shake again. Strain the cocktail into a chilled fizz glass or flute, then top with the club soda. Pinch the grapefruit twist over the drink and rub it around the rim of the glass, then discard the twist.